Effects of Environmental Enrichment on Learning a Discrimination Task by Captive White-spotted Bamboo Sharks (Chiloscyllium plagiosum)

Abstract

It has been demonstrated experimentally that several species of sharks are capable of learning by association but no studies have investigated the effects of environmental enrichment on sharks’ learning abilities. The main objective of this study was to test the hypothesis that environmental enrichment would improve learning performance in captivity of white-spotted bamboo sharks (Chiloscyllium plagiosum). During training and testing with a food reward before environmental enrichment, the sharks appeared to associate a discriminative stimulus (black vs. white tile) with food, but they did not discriminate between the tiles without a food reward. After a 68-d non-testing period followed by 10 d of exposure to enrichment objects (two plastic hula hoops) in the sharks’ tank, the experiment was repeated with the same result. There were no statistically significant differences in learning and memory before and after environmental enrichment. This negative result may have resulted from 1) small sample size (N=2 sharks), 2) ineffective enrichment objects, 3) insufficient time for enrichment effects to occur, or 4) inability of this species to learn a discrimination task. Future studies on enrichment should include larger sample sizes within species, multiple species of sharks, and testing with different enrichment objects.